1. Field of the Invention
The present invention relates to a power generation apparatus and a power generation system.
2. Description of the Related Art
Hitherto, as a power generation system that recovers power from low-temperature waste heat, a binary-cycle power generation system is known in which a working medium (cooling medium) having a low boiling temperature is evaporated by waste heat, an expander rotor is rotationally driven by steam of the working medium, and a power generator is driven by the rotation of the expander rotor. Japanese Patent Application Laid-Open No. 60-56104 discloses an example of the power generation system.
The power generation system of the related art includes an expander, a power generator, a condenser, a cooling medium supply pump, an evaporator, a separation tank, a lubricant supply pump, and a lubricant heating heat exchanger.
The expander includes a casing and a pair of expander rotors (screw rotors) accommodated in the casing. The steam of the cooling medium produced by the evaporator is suctioned into the casing, and the suctioned steam rotationally drives the pair of expander rotors by the expansion force thereof. In accordance with the rotation of the expander rotor, the power generator connected to the expander rotor is driven to generate power. Further, a lubricant is supplied into the casing so as to lubricate a bearing supporting a rotation shaft of the expander rotor or to seal respective portions inside the casing.
Since the lubricant supplied into the casing is discharged from the inside of the casing along with the steam of the cooling medium having been used to rotationally drive the expander rotor, a fluid mixture formed by mixing the lubricant and the steam of the cooling medium discharged from the inside of the casing is separated into the lubricant and the steam of the cooling medium in the separation tank. The steam of the cooling medium separated by the separation tank is discharged from the separation tank and is cooled and condensed by the condenser so as to become a liquid cooling medium. Then, the liquid cooling medium is sent to the evaporator by the cooling medium supply pump and is heated by the waste heat in the evaporator so as to produce steam of the cooling medium. The steam of the cooling medium produced by the evaporator is supplied into the casing of the expander. In this way, the cooling medium is circulated. Meanwhile, the lubricant which is separated by the separation tank is discharged from the separation tank and is sent to the casing of the expander through the heat exchanger by the lubricant supply pump.